source_unix_files (cs, bs, lib) source_file_exists Source files for this
library. The first part of the tuple is the file without extenstion for
modules and the second part is the source files matching (e.g. .ml and
.mli).

generated_unix_files ~ctxt source_file_exists has_native_dynlink
is_native ext_lib ext_dll (cs, bs, lib)
Compute all files expected by a build of the library. For each file a list
of alternatives is provided.